Radiographic imaging apparatus and control method therefor

ABSTRACT

A radiographic imaging apparatus comprising: a radiation detector configured to be detachable with respect to a patient platform and detect radiation transmitted through an object in one of a moving image capturing mode and a still image capturing mode; a detection unit configured to detect a shift timing of an image capturing mode; a cooling mechanism configured to cool the radiation detector in one of a first cooling mode and a second cooling mode having a higher cooling capacity than the first cooling mode; and a control unit configured to switch the cooling modes of the cooling mechanism based on detection by the detection unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radiographic imaging apparatus and acontrol method for the apparatus.

2. Description of the Related Art

Digital radiographic imaging apparatuses using DR (Digital Radiography)are mainly used for still image capturing. Such a digital radiographicimaging apparatus is smaller in size and lighter in weight than an I.I.TV imaging system having a similar imaging area, and hence is used formoving image capturing. Therefore, the market is demanding a radiationdetector that can perform both still image capturing using an electroniccassette (using DR) and moving image capturing that is performed whilethe cassette is placed on a table or platform.

An electronic cassette using DR requires higher power consumption whenperforming continuous shooting or moving image capturing than whenperforming still image capturing. For this reason, when this cassette isplaced on a support base such as a table or platform, a coolingmechanism is placed on the support base. There is known a technique ofcontrolling the driving of the cooling mechanism based on the detectionof a temperature inside the cassette (Japanese Patent Laid-Open No.2009-28234).

When an electronic cassette is used while being placed on a supportbase, the electronic cassette does not come into contact with a patient.For this reason, there is no need to satisfy the exterior temperaturerequirement for the electronic cassette. However, when the electroniccassette is removed from the support base, the electronic cassette needsto satisfy the exterior temperature requirement.

In general, as a cooling mechanism, a fan is often used because of itslow cost and simple arrangement. When, however, cooling is alwaysperformed by using the fan, motor sound noise and power consumption areuselessly large, resulting in inefficiency. This gives an object afeeling of discomfort. According to the technique disclosed in JapanesePatent Laid-Open No. 2009-28234 described above, for example, since onlya temperature detection result in a cassette is used as a controlcriterion for cooling, cooling is always performed to satisfy theexterior temperature requirement for the cassette regardless of whethermoving image capturing or still image capturing is performed. For thisreason, for example, unnecessary cooling is performed even at the timeof still image capturing.

SUMMARY OF THE INVENTION

The present invention provides a technique of switching the coolingmodes of an electronic cassette depending on whether moving imagecapturing or still image capturing is performed.

According to a first aspect of the present invention there is provided aradiographic imaging apparatus comprising: a radiation detectorconfigured to be detachable with respect to a patient platform anddetect radiation transmitted through an object in one of a moving imagecapturing mode and a still image capturing mode; a detection unitconfigured to detect a shift timing of an image capturing mode in theradiation detector; a cooling mechanism configured to cool the radiationdetector in one of a first cooling mode and a second cooling mode havinga higher cooling capacity than the first cooling mode; and a controlunit configured to switch the cooling modes of the cooling mechanismbased on detection by the detection unit.

According to a second aspect of the present invention there is provideda control method for a radiographic imaging apparatus, the methodcomprising: causing a radiation detector which is detachable withrespect to a patient platform to detect radiation transmitted through anobject in one of a moving image capturing mode and a still imagecapturing mode; causing a detection unit to detect a shift timing of animage capturing mode in the radiation detector; causing a coolingmechanism to cool the radiation detector in one of a first cooling modeand a second cooling mode having a higher cooling capacity than thefirst cooling mode; and causing a control unit to switch the coolingmodes of the cooling mechanism based on detection by the detection unit.

Further features of the present invention will be apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are views showing an example of the arrangement of aradiographic imaging apparatus according to an embodiment of the presentinvention;

FIG. 2 is a flowchart showing an example of the capturing operation ofthe radiographic imaging apparatus shown in FIG. 1A;

FIG. 3 is a graph showing an example of an outline of the temperaturedistribution of an electronic cassette exterior 6;

FIG. 4 is a view showing an example of the arrangement of a radiographicimaging apparatus according to the second examination; and

FIG. 5 is a flowchart showing an example of the capturing operation ofthe radiographic imaging apparatus according to the second embodiment.

DESCRIPTION OF THE EMBODIMENTS

An exemplary embodiment(s) of the present invention will now bedescribed in detail with reference to the drawings. It should be notedthat the relative arrangement of the components, the numericalexpressions and numerical values set forth in these embodiments do notlimit the scope of the present invention unless it is specificallystated otherwise.

The following embodiments will exemplify a case in which X-rays are usedas radiation. However, radiation is not limited to X-rays but may beelectromagnetic waves, α-rays, β-rays, or γ-rays.

First Embodiment

FIGS. 1A and 1B show an example of the arrangement of a radiographicimaging apparatus according to an embodiment of the present invention.

A radiographic imaging apparatus 20 includes a cooling controller 10 anda patient platform 7. The cooling controller 10 is communicativelyconnected to the patient platform 7 via a cable 11.

The patient platform 7 is a base to support a patient, in whichelectronic cassette (to be sometimes simply referred to as a cassette orradiation detector hereinafter) 100 is detachably mounted. As thepatient platform 7, for example, a decubitus table, standing-positionplatform, universal platform, or the like is used.

In this case, the electronic cassette 100 detects radiation transmittedthrough an object (an object to be examined in this embodiment) andacquires a radiation image based on the object. The electronic cassette100 is used while being mounted in the patient platform 7 and isportably used singly. In this embodiment, when the electronic cassette100 is portably used, still image capturing (a still image capturingmode) is performed, whereas when the electronic cassette 100 is usedwhile being mounted in the platform, moving image capturing (a movingimage capturing mode) is performed. In the case shown in FIG. 1A, a sidesurface of the patient platform 7 opens and closes, and the electroniccassette 100 is mounted in the patient platform 7 by being insertedthrough the side surface. In the case shown in FIG. 1B, the surface onthe radiation incident direction 1 side is open, and the electroniccassette 100 is mounted in the patient platform 7 by being insertedthrough this open surface. Note that the still image capturing mode is amode of performing one capturing operation for each radiation emission,whereas the moving image capturing mode is a mode of continuouslyperforming capturing operation for each radiation emission.

The patient platform 7 is provided with a detection unit 9. Thedetection unit 9 detects the shift timing of a capturing mode (themoving image capturing mode or still image capturing mode). In the caseshown in FIG. 1A, the detection unit 9 detects that the side surface ofthe patient platform 7 has opened. With this operation, the detectionunit 9 detects the shift timing of a capturing mode. Note that thedetection unit 9 may be placed on a portion where it comes into contactwith the operator when the electronic cassette 100 is detached/attached,for example, a handle portion. In this case, the side surface of thepatient platform 7 is preferably open, through which the electroniccassette 100 is detached/attached. In the case shown in FIG. 1B, thedetection unit 9 is placed on an end portion on the radiation incidentdirection 1 side of the patient platform 7. In this case, the detectionunit 9 is implemented by an infrared sensor or the like and detects thatthe object has reached a predetermined range. This detects the shifttiming of a capturing mode.

The electronic cassette 100 includes, in an exterior 6 thereof, anelectronic substrate 3, a support base 5, and a radiation detection unit2. Reference numeral 1 denotes the incident direction of radiation. Theradiation detection unit 2 detects the radiation transmitted through anobject. The electronic substrate 3 receives the signal detected by theradiation detection unit 2 via an electric signal line 4, and processesthe signal. The support base 5 supports the radiation detection unit 2.

The patient platform 7 is provided with a cooling mechanism 8 to cool anelectronic cassette exterior 6. The cooling mechanism 8 according tothis embodiment operates in two stages including a normal heatdissipation mode (first cooling mode) and a high heat dissipation mode(second cooling mode). The high heat dissipation mode is a mode with ahigher cooling capacity than that of the normal heat dissipation mode.The cooling mechanism 8 can be implemented by any mechanism, forexample, a contact type or non-contact type cooling mechanism such as aPeltier device, a fan, or water cooling mechanism. The disposition placeof the cooling mechanism 8 can be any surface excluding the surface onthe radiation incident direction 1 side of the patient platform 7. Inaddition, the cooling mechanism 8 may be disposed in the electroniccassette. Note that the cooling mechanism 8 in this embodiment will bedescribed by exemplifying a case in which the cooling mechanism to beused can adjust its output in two or more stages. However, the presentinvention is not limited to this. For example, it is possible to disposea plurality of cooling mechanisms 8 and selectively drive them. In thiscase, for example, in the normal heat dissipation mode, one coolingmechanism is driven. In the high heat dissipation mode, two or morecooling mechanisms are driven.

The cooling controller 10 controls the driving of the cooling mechanism8. The cooling controller 10 may be disposed in the patient platform 7.Note that the cooling controller 10 includes one or a plurality ofcomputers. The computer includes, for example, a main control unit suchas a CPU and storage units such as a ROM (Read Only Memory) and RAM(Random Access Memory). The computer may also include a communicationunit such as a network card and input/output units such as a keyboardand a display or a touch panel. Note that these components are connectedto each other via a bus or the like, and the main control unit executesprograms stored in the storage unit to control the components.

FIG. 2 is a flowchart showing an example of the capturing operation ofthe radiographic imaging apparatus 20 shown in FIG. 1A. For the sake ofdescriptive convenience, assume that image capturing has started whilean electronic cassette is mounted in the patient platform 7.

The radiographic imaging apparatus 20 captures a radiation image in themoving image capturing mode because the electronic cassette 100 ismounted in the patient platform 7. At this time, the cooling mechanism 8operates in the normal heat dissipation mode and cools the electroniccassette 100. This state continues until the detection unit 9 detectsthat the electronic cassette 100 has been removed from the patientplatform 7 or the user has issued an instruction to end image capturing(NO in step S2 after NO in step S1).

If the user issues an instruction to end image capturing (YES in stepS2), the radiographic imaging apparatus 20 terminates this processing.If the detection unit 9 detects the removal of the electronic cassette100 from the patient platform 7 (that is, the shift timing of the imagecapturing mode) (YES in step S1), the radiographic imaging apparatus 20notifies the cooling controller 10 of the corresponding information. Theradiographic imaging apparatus 20 shifts the image capturing mode to thestill image capturing mode (S3).

In this case, the cooling mechanism 8 starts operating in the high heatdissipation mode based on an instruction from the cooling controller 10(S4). This state continues until the detection unit 9 detects that theelectronic cassette 100 has been mounted in the patient platform 7 orthe user has issued an instruction to end image capturing (NO in step S6after NO in step S5). Note that, as described above, in the still imagecapturing mode, the radiographic imaging apparatus 20 performs imagecapturing while the object is in contact with the electronic cassetteexterior 6.

If the user issues an instruction to end image capturing (YES in stepS6), the radiographic imaging apparatus 20 terminates this processing.If the detection unit 9 detects that the patient platform 7 has beenmounted in the electronic cassette 100 (YES in step S5), theradiographic imaging apparatus 20 notifies the cooling controller 10 ofthe corresponding information, and shifts the image capturing mode tothe moving image capturing mode (S7). The cooling mechanism 8 startsoperating in the normal heat dissipation mode based on an instructionfrom the cooling controller 10 (S8). The radiographic imaging apparatus20 then returns to the processing in step S1 again.

FIG. 3 shows an example of an outline of the temperature distribution ofthe electronic cassette exterior 6.

Reference symbol T1 denotes an electronic cassette exterior temperaturespecified value. When the temperature rises above this specified value,it is necessary to prevent the electronic cassette from contacting theobject. Reference numeral H1 denotes a shift timing from the movingimage capturing mode to the still image capturing mode; H2, the timingat which the electronic cassette 100 has been actually removed from thepatient platform 7; L1, a relationship between the time and theelectronic cassette exterior temperature when the moving image capturingmode continues; and L2, a relationship between the time and theelectronic cassette exterior temperature when the normal heatdissipation mode shifts to the high heat dissipation mode at the timingH1.

As shown in FIG. 3, when the electronic cassette 100 is removed from thepatient platform 7, since the cooling mechanism 8 operates in the highheat dissipation mode, it is possible to satisfy the temperaturerequirement for the electronic cassette exterior 6.

As described above, according to the first embodiment, the cooling modeof the electronic cassette is switched in accordance with an imagecapturing mode. More specifically, when the electronic cassette mountedin the patient platform 7 is to be used, the normal heat dissipationmode is activated. When the electronic cassette is to be portably used,the high heat dissipation mode is activated. This can properly performcooling while suppressing power consumption, and hence can improve thecooling efficiency.

Second Embodiment

FIG. 4 is a graph showing an example of the arrangement of aradiographic imaging apparatus 20 according to the second embodiment.The same reference numerals as in FIG. 1A explaining the firstembodiment denote the same parts in FIG. 4, and a description of theparts may be omitted. Note that a description of the arrangementdescribed with reference to FIG. 1B will be omitted.

The radiographic imaging apparatus 20 according to the second embodimentis newly provided with a temperature sensor 14 and a lock mechanism 15.

The temperature sensor 14 detects the surface temperature of anelectronic cassette exterior 6 in particular. Although the temperaturesensor 14 according to the second embodiment is placed on an electronicsubstrate 3, since it is possible to calculate an electronic cassetteexterior temperature from the temperature distribution of the electroniccassette based on prior measurement, the sensor may be placed on anotherplace. For example, the sensor may be placed on the surface of anelectronic cassette 100 or at any position inside the cassette as longas the sensor does not interfere with image capturing.

The lock mechanism 15 locks the opening/closing door of a patientplatform 7 to inhibit the removal of the electronic cassette 100. Morespecifically, the lock mechanism 15 inhibits the opening/closing surfaceof the patient platform 7 from opening. Note that, for the case of thepatient platform (the opening/closing surface is the open surface)corresponding to FIG. 1B described in the first embodiment, a rotatableprojection on which an electronic cassette is caught may be placed as alock mechanism in the patient platform. Inhibiting the rotation of theprojection will inhibit the removal of the electronic cassette 100.

In addition to the operation in the first embodiment, a coolingcontroller 10 according to the second embodiment performs the operationof receiving a signal from the temperature sensor 14 and controlling thelock mechanism 15 based on the signal.

An example of the image capturing operation of the radiographic imagingapparatus 20 according to the second embodiment will be described nextwith reference to FIG. 5. Since the processing to be performed when theelectronic cassette 100 is portably used (while not being mounted in thepatient platform 7) differs from that in the first embodiment, theprocessing to be performed when the electronic cassette 100 is mountedin the patient platform 7 will be described below.

When the patient platform 7 is mounted in the electronic cassette 100(YES in step S11), the radiographic imaging apparatus 20 starts imagecapturing in the moving image capturing mode (S13). At this time, acooling mechanism 8 operates in the normal heat dissipation mode to coolthe electronic cassette 100 (S14). While the electronic cassette 100 ismounted in the patient platform 7, the temperature sensor 14 notifiesthe cooling controller 10 of the surface temperature detected from theelectronic cassette exterior 6, as needed.

While the electronic cassette 100 is mounted in the patient platform 7,the cooling controller 10 determines, based on the temperature notifiedfrom the temperature sensor 14, whether the temperature of theelectronic cassette exterior 6 satisfies a temperature requirement. Thatis, the cooling controller 10 determines whether the temperature of theelectronic cassette exterior 6 exceeds a predetermined temperature (doesnot satisfy the temperature requirement) or is lower or equal to thanthe predetermined temperature (satisfies the temperature requirement).

Upon determining that the temperature requirement is not satisfied (NOin step S15), the cooling controller 10 issues an instruction to operatein the high heat dissipation mode to the cooling mechanism 8, and alsoissues an instruction to lock to the lock mechanism 15. With thisoperation, the cooling mechanism 8 starts operating in the high heatdissipation mode (S16), and the lock mechanism 15 locks theopening/closing door (S17).

Upon determining in step S15 that the temperature requirement issatisfied (YES in step S15), the cooling controller 10 determineswhether the lock is being activated. If the lock is being activated (YESin step S18), the cooling controller 10 issues an instruction to operatein the normal heat dissipation mode to the cooling mechanism 8, and alsoissues an instruction to release the lock to the lock mechanism 15. Withthis operation, the cooling mechanism 8 starts operating in the normalheat dissipation mode (S19), and the lock mechanism 15 releases the lockof the opening/closing door (S20). Thereafter, the radiographic imagingapparatus 20 repeatedly executes the processing in steps S15 to S22until the detection unit 9 detects that the electronic cassette 100 hasbeen removed from the patient platform 7 or the user has issued aninstruction to end image capturing (NO in step S22 after NO in stepS21).

As described above, according to the second embodiment, even if thetemperature of the electronic cassette rises to an unexpectedly hightemperature due to long-time moving image capturing operation, a dutyerror, or the like, it is possible to satisfy the temperaturerequirement for the electronic cassette exterior 6. This can improve thesafety.

In the second embodiment described above, the radiographic imagingapparatus 20 is provided with the temperature sensor 14. However, it ispossible to omit the temperature sensor 14. In this case, the coolingcontroller 10 acquires an imaging condition history externally (forexample, from an RIS (Radiology Information System)) and calculates anecessary cooling time (the time required for dropping the temperatureof the electronic cassette to the specified temperature or lower) basedon the acquired history and the temperature characteristics of theelectronic cassette 100. When changing the image capturing mode(shifting from the moving image capturing mode to the still imagecapturing mode), the cooling controller 10 activates the lock during thecooling time, and releases the lock after the lapse of the cooling time.A supplementary description will be given with reference to FIG. 5. Inthe processing in step S16, the cooling controller 10 calculates anecessary cooling time (the difference between H1 and H2 in this case)based on the imaging condition history and the temperaturecharacteristics of the electronic cassette 100. The cooling controller10 then causes the cooling mechanism 8 to operate in the high heatdissipation mode and activates the lock during the calculated coolingtime. With this operation, when the electronic cassette 100 is removedfrom the patient platform 7, the temperature of the electronic cassetteexterior drops to satisfy the temperature requirement.

The typical embodiments of the present invention have been describedabove. However, the present invention is not limited to the embodimentsdescribed above and shown in the accompanying drawings, and can bemodified and executed as needed within the spirit and scope of theinvention.

For example, although the first and second embodiments have notparticularly referred to any arrangement using an RIS (RadiologyInformation System), it is possible to use information from the RIS. Forexample, the cooling controller 10 may acquire information such asimaging conditions for an examination to be made from the RIS,calculate, based on the information, the time at which the moving imagecapturing mode shifts to the still image capturing mode, and control thedriving of the cooling mechanism 8. This can eliminate the necessity ofthe temperature sensor and hence can achieve cost reduction. Inaddition, detecting a shift from the moving image capturing mode to thestill image capturing mode in advance makes it possible to start coolingfor the still image capturing mode in advance. This makes it possible toperform heat dissipation more efficiently.

In addition, the present invention can take embodiments as a system,apparatus, method, program, storage medium, and the like. The presentinvention can be applied to a system including a plurality of devices,or to an apparatus including a single device.

According to the present invention, it is possible to switch the coolingmodes of an electronic cassette depending on whether moving imagecapturing or still image capturing is performed.

Other Embodiments

Aspects of the present invention can also be realized by a computer of asystem or apparatus (or devices such as a CPU or MPU) that reads out andexecutes a program recorded on a memory device to perform the functionsof the above-described embodiment(s), and by a method, the steps ofwhich are performed by a computer of a system or apparatus by, forexample, reading out and executing a program recorded on a memory deviceto perform the functions of the above-described embodiment(s). For thispurpose, the program is provided to the computer for example via anetwork or from a recording medium of various types serving as thememory device (for example, computer-readable storage medium).

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2009-201089 filed on Aug. 31, 2009, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A radiographic imaging apparatus comprising: aradiation detector configured to be detachable with respect to a patientplatform and detect radiation transmitted through an object in one of amoving image capturing mode and a still image capturing mode; adetection unit configured to detect a shift timing of an image capturingmode in said radiation detector; a cooling mechanism configured to coolsaid radiation detector in one of a first cooling mode and a secondcooling mode having a higher cooling capacity than the first coolingmode; and a control unit configured to switch the cooling modes of saidcooling mechanism based on detection by said detection unit.
 2. Theapparatus according to claim 1, wherein said radiation detector operatesin the moving image capturing mode when being mounted in said patientplatform and operates in the still image capturing mode when beingportably used while being removed from said patient platform, and saidcontrol unit causes said cooling mechanism to operate in the secondcooling mode when said detection unit detects a shift timing from themoving image capturing mode to the still image capturing mode, andcauses said cooling mechanism to operate in the first cooling mode whensaid detection unit detects a shift timing from the still imagecapturing mode to the moving image capturing mode.
 3. The apparatusaccording to claim 1, wherein said detection unit detects a shift timingof the image capturing mode based on whether said radiation detector ismounted in or removed from said patient platform.
 4. The apparatusaccording to claim 1, wherein said detection unit detects a shift timingof the image capturing mode based on information including an externallyacquired imaging condition.
 5. The apparatus according to claim 1,wherein said detection unit detects a shift timing of the imagecapturing mode based on an approach of said radiation detector to apredetermined range of the object.
 6. The apparatus according to claim1, further comprising a temperature sensor configured to detect asurface temperature of said radiation detector, and a lock mechanismconfigured to activate a lock to inhibit said radiation detector frombeing removed from said patient platform, wherein said control unit, inthe case than said radiation detector is mounted in said patientplatform, causes said lock mechanism to activate the lock while causingsaid cooling mechanism to operate in the second cooling mode when atemperature from said temperature sensor exceeds a predeterminedtemperature, and causes said lock mechanism to release the lock whilecausing said cooling mechanism to operate in the first cooling mode whena temperature from said temperature sensor is lower than or equal tosaid predetermined temperature.
 7. The apparatus according to claim 2,further comprising a lock mechanism configured to activate a lock toinhibit said radiation detector from being removed from said patientplatform, wherein said control unit causes said lock mechanism to activethe lock during a time which is calculated based on an externallyacquired imaging condition history and required for dropping atemperature of said cooling mechanism to lower than or equal to apredetermined temperature, when said radiation detector is mounted insaid patient platform and said detection unit detects a shift timingfrom the moving image capturing mode to the still image capturing mode.8. A control method for a radiographic imaging apparatus, the methodcomprising: causing a radiation detector which is detachable withrespect to a patient platform to detect radiation transmitted through anobject in one of a moving image capturing mode and a still imagecapturing mode; causing a detection unit to detect a shift timing of animage capturing mode in the radiation detector; causing a coolingmechanism to cool the radiation detector in one of a first cooling modeand a second cooling mode having a higher cooling capacity than thefirst cooling mode; and causing a control unit to switch the coolingmodes of the cooling mechanism based on detection by the detection unit.